On the other hand, pantograph, traction, door, brake, coupling, battery and bogie systems are produced by a few world-wide companies and preferred due to broad usage and quality. These systems are mainly the most critical and expensive parts of rolling stock.

Nevertheless, localization may reach up to 60%, as can be seen in Bursa cars. Local production also drops the maintenance and repair costs, which become an important expense item in following years.

Some companies like Siemens, which are out of the tenders due to local production term are studying investment in Turkey.